Surface photovoltage spectra and interface deep levels for InP/Cs interface

The surface photovoltage method is used to determine the energy spectrum of interface levels arising in the bandgap of InP under the formation of InP interface with Cs,:the metal which does not react with InP. At early stage of the interface formation after deposition of submonolayers of Cs atoms two filled interface levels have been found. This spectrum differs from spectra of interface levels for interfaces of InP with strongly reactive metals such as Cu and Pd where earlier [3,4] four interface levels have been found. The reason for the difference between these interface level spectra is discussed.